In U.S. Pat. No. 4,256,537, which issued Mar. 17, 1981 and which is incorporated herein by reference, there is disclosed an apparatus for stretching and tensioning an endless web, such as a blanket. The apparatus includes a support for supporting the endless web at a first location, a roll for supporting the endless web at a second location, and a carriage movable along a track (which extends between the first and second locations) for rotatably supporting the roll in a normal operating position and for moving the roll relative to the support means. The carriage means includes a first carriage section and a second carriage section engaged with the track. The first carriage section includes a roll support means for lifting one end of the roll to a position above the normal operating position. The second carriage section includes a second roll support means for maintaining the roll in the lifted position without support of the first roll support means so that the endless web may be removed. This is preferably accomplished by a support arm which extends from the second carriage section and a movable saddle element supported on the support arm for engaging the underside of and supporting the roll in the lifted position.
While the apparatus disclosed in the aforesaid patent was an improvement over prior systems, it has proven to be relatively expensive to manufacture. Additionally, it is believed to be relatively inefficient to provide an elaborate and expensive jacking apparatus in the first carriage section and to provide a separate and independent support arm mechanism at a remote location which serves the sole purpose of holding the roll in an elevated position once it has reached that elevated position.
Accordingly, it is an object of the present invention to provide an improved apparatus for stretching an endless web which overcomes the aforesaid problems and improves upon the apparatus disclosed in U.S. Pat. No. 4,256,537.
It is a further object of the present invention to provide such an apparatus which is less expensive to manufacture than the aforesaid device.
It is another object of the present invention to provide such an apparatus in which the mechanisms for lifting the roll to an elevated position and for retaining the roll in the elevated position are within the same mechanism.
Various other objects and advantages of the present invention will become clear from the following detailed description of several exemplary embodiments thereof, and the novel features will be particularly pointed out in conjunction with the claims appended hereto.